1. Field of the Invention
The present invention relates to an inverter apparatus for converting a DC input voltage to an AC voltage and supplying the AC voltage to a load, and more particularly to, an inverter apparatus for driving a plurality of loads.
2. Description of the Related Art
Recently, as a substitute for CRT televisions, thin, wide screen liquid crystal televisions have been widely provided. As a backlight for the liquid crystal television, a plurality of cold cathode fluorescent lamps (hereinafter, referred to as CCFLs) or a plurality of external electrode fluorescent lamps (hereinafter, referred to as EEFLs) are disposed on a rear surface of a liquid crystal panel.
An inverter (DC/AC converter) which boosts up a DC voltage of about 12V and outputs an AC voltage is used for driving the fluorescent lamp such as the CCFL and the EEFL. The inverter converts a current flowing through the fluorescent lamp to a voltage and feed the voltage back to a control circuit, so that turning-on and turning-off of a switching element are controlled based on the feedback voltage. The related technologies are disclosed in Japanese Patent Application Laid-Open No. 2003-323994, International Publication Pamphlet No. 2005/038828, and Japanese Patent Application Laid-Open Nos. 2002-134293 and 2004-335422.                [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-323994        [Patent Document 2] International Publication Pamphlet No. 2005/038828        [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-134293        [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-335422        
Now, a case where a plurality of fluorescent lamps are driven by using an AC voltage boosted by an inverter is considered. Luminance of each fluorescent lamp is determined by a current flowing through each fluorescent lamp. In order to obtain uniform or desired different luminance of a plurality of the fluorescent lamps, the currents flowing through the fluorescent lamps need to be controlled.
However, in a case where the currents flowing through a plurality of the fluorescent lamps are individually controlled in a feedback manner, control circuits need to be provided to the respective fluorescent lamps. In applications such as a liquid crystal television or a liquid crystal monitor, several or tens of fluorescent lamps are lighted simultaneously. In this case, if a plurality of the control circuits are incorporated in the liquid crystal television, there are disadvantages in terms of mounting area, cost, and power consumption.